To a mixture of alkene coumpound (284 mg, 0.72 mmol) in t-BuOH (1.8 mL) and THF (0.6 mL) at room temperature was added
N-methylmorpholine N-oxide (337 mg, 1.44 mmol) followed by osmium tetroxide (0.027 mL, 0.022 mmol). The mixture was stirred at room temperature overnight. The
reaction was then diluted with phosphate buffer (pH 7, 5 mL). Sodium periodate (693 mg, 3.24 mmol) was then added and the cloudy solution was stirred vigorously for 2 hours. Next
it was diluted with water and extracted three times with ethyl acetate. The combined organics were dried over Na2SO4, filtered and concentrated in vacuo to give aldehyde compound as a yellow
solid (251 mg, 88%).

A 200 mL round bottom flask was charged with a magnetic stir bar, 3-ethoxy-2- fluorobenzonitrile (1.000 g, 6.05 mmol), and anhydrous toluene (12.92 ml). The
solution was placed under argon and cooled to 0°C with an ice bath. DIBAL-H (7.27 ml, 7.27 mmol) (1M in PhMe) was then added drop wise via syringe and the reaction was
allowed to stir to rt overnight. To this mixture was added 10 % HCl until the solution reached a pH of ~ 2. The resulting mixture was then left to stir for 0.5 h. and was then poured into a
separatory funnel and extracted with ethyl acetate (2 x 200 mL). The combined organic extract was dried with MgSO4, filtered, and concentrated in vacuo to yield the crude product which
was purified via silica gel chromatography (80 g) using ethyl acetate/hexanes (1:4) as eluent to provide pure 3-ethoxy-2-fluorobenzaldehyde (0.810 g, 80 %).